May  IS,  1912. 


U.  S.  DEPARTMENT  OF  AGRICULTURE, 

BUREAU   OF   ENTOMOLOGY— CIRCULAR  No.  153. 

L.  O.  HOWARD.  Entomologist  »nd  Chid  of  Bureau. 


THE  COTTON  WORM  OR  COTTON  CATERPILLAR. 

(Alabama  argillacc a  Ilulm.). 


W.  D.  HUNTER, 

In  Charge  of  Southern  Field  Crop  Insect  Investigations. 


—12 


WASHINGTON   :  GOVERNMENT  PRINTING  OFFICE  I  1012 


B  UREA  U  OF  ENTOMOLOG  Y. 

L.  O.  Howard,  Entomologist  and  Chief  of  Bureau. 

C.  L.  Marlatt,  Entomologist  and  Acting  Chief  in  Absence  of  Chief. 

R.  S.  Clifton,  Executive  Assistant. 

W.  F.  Tastet,  Chief  Clerk. 

F.  H.  Chittenden,  in  charge  of  truck  crop  and  stored  product  insect  investigations. 

A.  D.  Hopkins,  in  charge  of  forest  insect  investigations. 

W.  D.  Hunter,  in  charge  of  southern  field  crop  insect  investigations. 

F.  M.  Webster,  in  charge  of  cereal  and  forage  insert  investigations. 

A.  L.  Quaintance,  in  charge  of  deciduous  fruit  insect  investigations. 

E.  F.  Phillips,  in  charge  of  bee  culture. 

D.  M.  Rogers,  in  charge  of  preventing  spread  of  moths,  field  ivork. 
Rolla  P.  Currie,  in  charge  of  editorial  work. 

Mabel  Colcord,  in  charge  of  library. 

Southern  Field  Crop  Insect  Investigations. 
W.  D.  Hunter,  in  charge. 

F.  C.  Bishopp,  A.  H.  Jennings,  H.  P.  Wood,  W.  V.  King,  engaged  in  tick  life-history 
investigations. 

W.  D.  Pierce,  G.  D.  Smith,  J.  D.  Mitchell,  Harry  Pinkus,  B.  R.  Coad,  R.  W. 

Moreland,  engaged  in  cotton-boll  weevil  investigations. 
A.  C.  Morgan,  G.  A.  Runner,  S.  E.  Crumb,  D.  C.  Parman,  engaged  in  tobacco  insect 

investigations. 
T.  E.  Holloway,  E.  R.  Barber,  engaged  in  sugar-cane  insect  investigations. 

E.  A.   McGregor,  W.  A.  Thomas,  engaged  in  red  spider  and  other   cotton  insect 
investigations. 

J.  L.  Webb,  engaged  in  rice  insect  investigations. 

R.  A.  Cooley,  D.  L.  Van  Dine,  A.  F.  Conradi,  C.  C.  Krumbhaar,  collaborators. 

I! 


Circular  No.  153.  lsMU"'  Mu>  ».  ''"^ 

United  States  Department  of  Agriculture, 

BUREAU  OF  ENTOMOLOGY. 
L.  O.  HOWARD,  Entomologist  and  Chief  of  Bureau. 


THE  COTTON  WORM  OK  COTTON  CATERPILLAR. 

I  abai  ]illa>  ea  Eubn 

By  W.  D.  Hi  mi  k. 
In  Charge  of  Southern  Field  Crop  Insect  Investigations. 

LNTR(  »D1  i   I  H).\. 

The  cotton  worm,  or  cotton  caterpillar,  also  bul  incorrectly  called 
the  "army  worm,"  has  been  known  to  cotton  planters  in  the  United 
States  since  1793.  Before  the  invasion  by  the  boll  weevil  it  and  the 
bollworm  were  by  all  odds  the  most  destructive  cotton  insects  in 
this  country.  During  sonic  seasons  the  damage  by  the  caterpillar 
began  as  early  as  June  and  occasionally  the  field's  were  completely 
defoliated  by  the  middle  of  July.  The  destructiveness  of  the  insect 
and  the  consternation  caused  among  cotton  planters  by  its  ravages 
are  well  described  in  an  account  published  by  Mr.  Thomas  Affleck  of 
Washington,  Miss.,  in  the  American  Agriculturist  of  September  9, 
1846: 

The  caterpillar,  cotton  worm,  cotton  moth,  or  chenille  i  f  the  French  Wesl  Indies, 
Guiana,  etc.,  has  utterly  blighted  the  hopes  of  the  cotton  planter  for  the  presenl  year, 
and  produced  most  anxious  fears  for  the  future.  I  have  hoard  from  the  greater  part, 
of  the  rolton-Lirowiim  region — the  news  is  all  alike — the  worm  has  destroyed  the  crop. 
I  have  no  idea  that  any  considerable  portion  of  any  State  will  escape.  *  *  *  The 
present  year  the  crop  is  unusually  backward,  at  least  four  works  later  than  usual. 
We  have  but  just  commenced  picking,  usually  beginning  aboul  the  lasl  week  in  July 
or  the  first  week  inAugust.     A.1  thismon  rj  field  within  this  region  of  country, 

say,  south  of  Vicksburg,  is  stripped  of  everything  but  the  stems,  the  larger  branches, 
and  a  few  of  the  first  bolls,  already  too  hard  for  the  worm     powei    Ema  tii  ition      The 
full-grown  bolls  noi  yel  become  hard  are  completely  eaten  out,  a  circumstance  1  have 
heard  of  but  once  before,  in  L825.    The  fields  present  a  most  melancholy  appear- 
looking  from  the  bluff  at  Nat  -  the  river  to  those  tine  plantation-  Lack 

of  Vidalia,  nothing  i-  to  be  "<-w  bul  the  brown  withered  skeleton  of  the  plant. 

Until  about  ls?l  no  satisfactory  methods  of  combating  the  cotton 
caterpillar  had  been  discovered.  Many  fallacious  remedies,  such  as 
attracting  the  moths  to  large  tiro  in  the  fields,  were  more  or  li  -,  in 
ii-'     hut   the  onl\   ones  of  even  the  slightest  value  were  brushino  the 


2  THE  COTTON  WORM  OR  COTTON  CATERPILLAR. 

insects  from  the  plants  and  preventing  their  invasion  of  the  fields 
by  means  of  ditches.  Early  in  the  seventies  the  whole  situation  was 
revolutionized  by  the  discovery  that  the  worms  could  be  poisoned 
quickly  and  economically  by  the  use  of  Paris  green  or  other  arsenical 
compounds.  The  practice  of  controlling  the  insect  by  these  means 
soon  became  universal  in  the  South.  Planters  everywhere  obtained 
large  supplies  of  poison  each  season  exactly  as  other  regular  plan- 
tation supplies  were  procured.  As  soon  as  the  defoliation  began  the 
poisons  were  applied.  This  checked  the  outbreak  on  the  plantation 
at  the  beginning,  whereas  without  the  use  of  the  arsenicals  it  would 
have  spread  over  the  entire  cotton  acreage.  About  the  same  time 
certain  changes  in  agriculture  in  the  South  also  contributed  in  a 
very  decided  manner  to  the  reduction  of  the  importance  of  the  pest. 
The  large  cotton  fields  began  to  be  broken  up  into  smaller  fields 
planted  to  a  variety  of  crops.  This  system  of  diversification  of 
itself  prevented  such  great  increase  in  the  number  of  the  worms  as 
had  taken  place  in  previous  years.  These  two  facts  together  seemed 
to  indicate  for  many  years  that  the  cotton  worm  was  no  longer  to 
be  feared  as  an  important  enemy  of  the  cotton  plant  in  the  United 
States. 

For  21  years  prior  to  1911  the  cotton  worm  had  not  been  generally 
abundant  in  the  United  States,  although  there  was  local  damage 
of  some  severity  during  different  years  in  that  period.  Indeed  the 
passing  of  the  insect  had  come  to  be  considered  such  a  settled  fact 
that  the  outbreak  of  1911  was  as  surprising  to  the  cotton  planters 
as  to  entomologists. 

THE    OUTBREAK   OF    1911. 

The  outbreak  of  1911  did  not  originate  in  the  United  States,  but 
in  Central  or  South  America.  The  moths  flew  northward  very 
early  in  the  season  and  reached  the  neighborhood  of  Brownsville, 
in  Texas,  by  April.  By  the  middle  of  June  practically  all  of  the 
cotton  fields  in  the  vicinity  of  Brownsville  that  had  not  been  pro- 
tected by  the  use  of  poisons  had  become  defoliated.  The  new  gene- 
rations of  the  insects  flew  northward  and  eastward  during  June  and 
July.  During  the  latter  month  there  appears  also  to  have  been 
another  invasion  of  the  United  States  from  South  America.  This 
reinvasion  took  the  moths  into  the  South  Atlantic  States,  where 
they  were  soon  found  in  very  great  numbers.  They  bred  with  great 
rapidity  and  spread  northward  and  westward.  In  August  the  west- 
ern and  eastern  invasions  coalesced,  and  within  a  few  weeks  the 
insects  were  numerous  in  cotton  fields  throughout  the  belt. 

Later  in  the  season  many  of  the  moths  which  developed  in  the 
cotton  fields  of  the  South  flew  northward,  where  they  attracted  con- 
siderable  attention.     Millions   of  individuals   were  found  in  Wash- 


I  III.    COTTON    WORM    OB    COTTOK    I    \  I  I  KIM  l.l.AK.  6 

ington,  D.  ('..  between  September  L9  and  October  29.  On  Sep- 
tember 23  they  were  observed  at  Pittsburgh,  Pa.,  and  at  Philadel- 
phia on  the  same  date.  By  September  25  they  were  found  in  great 
numbers  in  New  Haven,  Conn.,  and  on  October  13  at  Orono,  Me. 
Large  numbers  of  specimens  were  observed  in  September  al  Mil- 
waukee, Wis.,  and  also  al   Ottawa,  Canada. 

Many  of  the  moths  which  Hew  northward  were  found  upon  fruits 
of  various  kinds,  which  they  punctured  for  the  purpose  of  feeding. 
Peaches,  apples,  grapes,  and  other  fruits  were  at  tucked  in  this 
manner  and  fears  arose  among  fruit  growers  that  an  important  new- 
pest  had  appeared. 

POSSIBILITY     OF     W    OUTBREAK    l\     L912. 

The  cotton  moth  is  of  South  American  origin  and  does  not  survive 
the  winters  in  the  United  States,  except  when  the  temperatures  are 
above  the  normal  or  when  individuals  obtain  unusual  shelter. 
Whether  there  will  be  an  outbreak  in  L912  depends  upon  two  con- 
tingencies: First,  whether  any  of  the  moths  bred  in  t'.Hi  succeeded 
in  surviving  the  winter  in  this  country;  and.  second,  whether  a  new 
invasion  from  South  America  takes  place. 

Careful  searches  for  the  moth  have  been  made  in  favorable  locali- 
ties in  the  southern  part  of  the  cotton  bell  during  the  past  winter. 
This  investigation  ha-  extended  from  Brownsville,  Tex.,  to  South 
Carolina.  No  live  moths  have  been  found.  Mr.  J.  D.  Mitchell,  of 
this  bureau,  placed  chrysalides  of  the  moth  in  rearing  cages  at  Vic- 
toria, Tex.,  in  the  fall  of  I'M  i  ;m,|  found  that  by  the  (Mid  of  January 
they  were  all  killed  by  the  cold.  These  two  fact-  seem  to  indicate 
thai  all  'if  the  mot h-  produced  in  the  United  States  in  191]  failed  to 
survive  t  be  winter. 

It  is  extremely  difficult,  however,  to  find  the  moth  in  hibernating 
quarters,  and   the  failure  to  find  specimens  is  far  from  conclusive 

proof  that  they  do  ii"1  e\i-l;  but  there  i-  another  consideration 
which  bear-  out  the  conclusion  that  the  mot  lis  bred  in  this  country 
in  1011  were  all  killed  during  the  winter.  This  b  that  the  history  of 
the  outbreaks  of  the  cotton  worm  in  the  United  State-  show  that  the 
insects  were  all  killed  during  winters  in  which  the  temperature 
below  the  normal.  The  winter  of  1911-12  was  abnormally  cold 
throughout  I  he  cotton  bi 

Our  conclusion,  therefore,  from  all  sources  of  information  on  which 
dependence  can  be  placed,  is  that  the  only  fear  of  an  outbreak  during 
l'.'l'-  i-  in  a  reinvasion  of  the  United  States  from  more  southern 
Localities.  There  i-  "iir  fad  which  seems  t"  indicate  that  there  may 
possibly  be  such  a  reinvasion.  The  chronology  of  the  outbreaks  of 
the  insect  in  this  country  from  the  earlier  accounts  shows  a  distinct 


4  THE  COTTON  WORM  OR  COTTON  CATERPILLAR. 

tendency  toward  the  recurrence  of  a  series  of  two  or  three  seasons  of 
abundance.  Apparently  the  species  reaches  great  numbers  in  South 
America  and  remains  abundant  for  several  years,  thus  giving  rise  to 
the  consecutive  swarms  which  have  invaded  the  United  States. 
Since  the  region  in  which  this  occurrence  takes  place  is  far  beyond 
the  influence  of  the  recent  cold  weather  in  the  United  States,  we  may 
suppose  that  the  past  history  of  the  insect  may  be  repeated  and  that 
another  invasion  may  be  expected  during  1912.  This  would  seem  to 
be  especially  probable  in  case  the  temperatures  of  the  spring  months 
should  be  above  the  normal. 

We  do  not  wish  to  be  understood  as  predicting  an  outbreak  during 
the  present  season.  The  facts  we  have  noted  seem  to  indicate  that 
such  may  take  place,  but,  on  the  whole,  our  position  is  that  of  giving 
a  warning  rather  than  a  prediction.  In  order  to  be  on  the  safe  side 
it  is  advised  that  planters  make  the  necessary  preparations  for  fighting 
the  worm  and  that  they  begin  operations  at  the  earliest  possible 
moment. 

THE    COTTON    CATERPILLAR   AND   THE    BOLL    WEEVIL. 

In  regions  where  the  boll  weevil  occurs  the  cotton  caterpillar  is  not 
an  unmixed  evil.  On  the  contrary,  it  generally  acts  as  a  decided 
check  against  the  boll  weevil.  The  defoliation  of  the  plants  drives 
many  of  the  weevils  out  of  the  field  and  allows  the  sun  to  destroy 
numerous  immature  stages  in  fallen  squares  on  the  ground.  In  fact, 
where  the  defoliation  is  complete  the  boll  weevil  receives  almost  as 
serious  a  setback  as  happens  when  the  planter  destroys  the  cotton 
stalks  in  the  fall.  It  must  be  noted,  however,  that  there  is  a  point 
beyond  which,  even  in  boll-weevil  regions,  the  cotton  worm  is  not  a 
benefit  to  the  crop.  Where  the  defoliation  begins  early  in  the  season 
the  plants  may  be  prevented  from  maturing  the  bolls,  and  thus  the 
damage  by  the  one  insect  is  merely  added  to  that  of  the  other. 

In  regions  where  the  boll  weevil  is  abundant  our  advice  is  that  planters 
do  not  poison  the  cotton  for  the  leaf  worm,  unless  it  becomes  numerous 
by  the  time  the  earliest  bolls  are  about  three-fourths  grown.  Where 
the  boll  weevil  is  present  but  not  in  great  numbers  the  poisoning 
should  be  done  at  a  relatively  early  date. 

DESCRIPTION    OF   THE    STAGES    OF   THE    COTTON    MOTH. 

The  egg. — The  egg  is  light  green  in  color  and  contrasts  with  the  color 
of  the  cotton  leaf,  so  that  it  is  easily  detected  by  the  practiced  eve. 
The  eggs  are  generally  placed  on  the  underside  of  the  leaves,  never 
in  clusters.  The  female  deposits  about  500  eggs.  The  duration  of  the 
c^rg  stage  varies  with  the  temperature,  ranging  from  3  days  to  more 
than  20. 


THE  COTTON  WORM  OB  COTTON  CATERPILLAR.  5 

Tin  larva.  The  larvae  <>f  the  cotton  moth  vary  greatly  in  size  and 
coloration,  but  there  are  certain  characteristic  marks  that  enable  one 
to  determine  the  species.  (See  fig.  1.)  Early  in  the  season  the 
larva-  are  yellowish-green  and  aol  provided  with  conspicuous  mark- 
ings. A-  a  matter  of  fact,  individuals  without  conspicuous  markings 
may  he  found  in  the  cotton  fields  throughout  the  season.  The  form 
generally  seen,  however,  may  he  described  as  follows:  Length  about 
11  inches,  upper  surface  with  a  broad  brownish  or  perfectly  black 
stripe.  Down  the  center  of  the  stripe  is  a  line  yellowish  line  and 
similar  lines  hound  the  black  area  on  either  side.  Each  segmenl  as 
seen  from  above  -how-  four  black  dot-,,  which,  of  course,  are  much 
more  conspicuous  where  the  dorsal  black  stripe  is  less  distinct.  When 
viewed  from  the  side  each  segment  shows  four  black  dot-  similar  to 
those  on  the  dorsal  surface,  hut  somewhat  smaller  in  size. 

The  larvae  feed  by  preference  upon  the  cotton  leaves.  In  eases 
whore  they  are  so  abundant  that  the  leaves  are  destroyed  they  feed 
upon  the  squares  and  bolls  and  even  the  twigs.  In  t  he  case  ><(  attack 
on  bolls  only  the  outer  surface  is  devoured.  On  this  account  the 
work  of  t  he  cot  ton  worm  on  bolls  can  be  dist  inguished  from  that  of  the 
bollworm.  The  latter  species  gnaws  a  hole  directly  through  the  out- 
side of  the  boll  and  feeds  upon  the  interior. 

Careful  investigations  have  shown  that  the  cotton  worm  feeds  only 
upon  the  cotton  plant.  In  many  cases  where  attempts  were  made  to 
breed  it  on  other  plants  failure  resulted.  In  one  instance  Mr.  E.  A- 
Schwarz  succeeded  in  causing  a  larva  to  develop  tot  he  chrysalis  stage 
on  morning-glory  (Ipomata  sp.).  The  chrysalis,  however,  was  imper- 
fect and  failed  to  develop.  The  statement  is  frequently  made  that 
the  cotton  caterpillar  feeds  upon  pokeweed  i  Phytolacca  sp.)  and  other 
plants.  Such  reports  are  due  to  mistaking  some  other  insects  for  the 
cotton  pest . 

When  the  worms  are  numerous  and  a  cotton  held  has  been  defo- 
liated the\  frequently  travel  over  the  ground  in  great  numbers  in 
search  of  food.  This  habit  is  the  cause  of  the  local  use  of  the  term 
"army  worm  "  for  t  he  insect. 

77/.  chrysalis  or  pupa.  The  cotton  caterpillar  transforms  to  the 
pupal  stage  on  the  cotton  plant.  Unlike  t  he  bollworm,  it  never  enters 
the  ground  for  this  purpose.  Usually  it  vpins  a  crude  web,  using  a 
portion  df  the  cotton  leaf  for  the  purpose,  hut  in  many  cases  no  web 
whatever  is  formed,  and  1  he  naked  pupa  hangs  from  t  he  col  ton  plant- 

by  means  of  a  thread  spun  by  the  larva  for  t  he  purpose.     (See  lii,r.  1 .) 
The  duration  of  the  pupal  stage  is  from  one  to  four  weeks. 

Tin  adult.  The  adult,  of  the  cotton  worm  is  a  moth,  the  wings  of 
which  expand  from  LJ  to  il  inches.  See  fig.  ].)  The  general 
color  is  brownish-yellow  or  tawny,  in  many  specimens  showing  a 
somewhat  crimson  hue.     The  most  conspicuous  feature  of  the  upper 


THE  COTTON  WORM  OR  COTTON  CATERPILLAR. 


Fig.  1.— The  cotton  worm  (A labamaargillacca):         ■     md  work,    (original.) 


THE    COTTON    WORM    OB    COTTON    I    \  I  ERPIL]   \i;. 

surface  is  a  distincl  black  spol  on  the  anterior  wings  jusl  beyond 
the  middle  and  aboul  one-third  of  the  distance  from  the  anterior  to 
the  posterior  margins.  The  fronl  wings  are  also  ornamented  with  a 
number  of  transverse  zigzag  lines.  The  mosl  conspicuous  of  these 
arc  one  which  crosses  the  anterior  half  of  the  wing  immediately  be- 
yond the  eye  spol  and  another  which  extends  from  just  behind  the 
eye  spol  to  the  posterior  margin.  In  specimens  which  have  become 
rubbed  these  transverse  markings  are  sometimes  indiscernible. 

The  moth  is  nocturnal  in  its  habits  and  has  remarkable  powers  of 
flight.  This  is  show  n  l»\  its  crossing  t  he  <  rulf  of  Mexico  and  reaching 
localities  iii  the  northern  United  States  and  Canada. 

Unlike  the  great  majority  of  moths  the  proboscis  of  this  species  is 
strengthened,  so  thai  it  can  puncture  such  substances  as  green  pears 
or  apples,  in  [911  and  various  earlier  years  in  which  invasion-  of 
northern  localities  took  place  the  damage  to  fruit  in  some  cases  was 
considerable. 

PASSING    THE    WIN  IKK. 

Whenever  the  cotton  worm  passes  the  winter  in  the  United  States 
ii  is  in  the  adult  stage.  In  this  it  is  unlike  the  bollworm  and  other 
species,  which  pass  the  winter  in  the  pupal  stage  in  the  ground. 

The  question  of  whether  the  cotton  moth  hibernates  normally  in 
the  United  States  is  one  thai  was  discussed  at  greal  length  by  entomol- 
ogists and  planters  in  former  years.  The  early  records  and  recent 
observations  all  seem  to  hear  out  the  belief  thai  the  insect  is  in  no 
sense  a  incm her  of  the  North  American  fauna,  ami  thai  it  can  survive 
the  winter  in  this  country  only  when  the  temperatures  are  favorable. 
In  fact,  there  is  only  one  authentic  record  of  the  moths  surviving  the 
winter  in  this  country.  This  was  the  winter  of  1881  82,  which  was 
unusually  mild.  During  thai  winter  live  moths  were  found  in  the 
vicinity  of  Archer,  Fla.,  during  every  month  of  the  winter  up  to  March, 
and  young  larvse  were  found  a1  work  on  volunteer  cotton  at  the  end 
of  that  month. 

CONTROL. 

The  control  of  the  cotton  caterpillar  is  not   at  all  difficult.     The 
methods  to  be  described  are  simple  and  inexpensive.     Consequently 
there  is  no  reason  why  every  planter  should  not  check  the  damage  i 
the  beginning. 

I>\  far  the  he- 1  method  of  control  is  by  the  use  of  powdered  arsenate 
of  load.  This  substance  has  several  decided  advantages  over  any 
other  poison-  that  could  be  used.  It  does  nol  injure  the  foliage  to  any 
extent  whatever,  and  adheres  to  the  leave-  in  -pile  of  considerable 
rainfall.  In  both  these  respects  it  is  much  to  !„■  preferred  to  Paris 
green,  which  i-  likely  to  injure  the  foliage  and  which  does  not  adhere 

to  the  leaves  well  except    when  mixed  with  Hour. 


8  THE  COTTO>~  WORM  OB  COTTON  CATERPILLAR. 

Powdered  arsenate  of  lead  should  be  applied  at  the  rate  of  about 
2  pounds  per  acre,  more  or  less,  depending  upon  the  size  of  the  cotton. 
It  is  best  to  make  the  application  when  the  leaves  are  moist  with 
dew.  as  is  generally  the  case  early  in  the  morning.  The  less  wind 
there  is  the  less  will  be  the  loss  from  the  poison  which  drifts  onto  the 
ground.     Therefore  a  calm  time  should  be  selected. 

The  earlier  the  application  of  arsenicals  can  be  made  the  better 
it  will  be.  The  planter  should  not  wait  until  extensive  defoliation 
has  taken  place.  A  watch  should  be  kept  upon  the  low  moist  areas, 
where  the  worms  invariably  appear  first.  As  soon  as  the  destruction 
of  the  leaves  becomes  evident  in  such  places  the  poison  should  be 
applied.  By  this  means  the  outbreak  may  be  checked,  and  the 
necessity  of  poisoning  the  total  acreage  on  the  plantation  may  be 
avoided. 

After  powdered  arsenate  of  lead  the  best  insecticide  for  the  cotton 
caterpillar  is  Paris  green.  As  has  been  indicated,  however,  even 
small  amounts  of  this  substance  are  likely  to  injure  the  foliage. 
Such  injury  may  not  become  apparent  until  several  weeks  after  the 
application.  Nevertheless,  the  burning  of  the  tender  leaves  will 
show  eventually  in  the  stunted  condition  of  the  plants.  This  diffi- 
culty may  be  overcome  to  some  extent  by  the  use  of  air-slaked  lime 
and  Paris  green  in  equal  parts.  Whether  the  lime  is  used  or  not, 
flour  should  be  used  with  the  Paris  green  in  equal  parts.  This  will 
assist  greatly  in  causing  the  poison  to  adhere  to  the  foliage. 

London  purple  can  also  be  used,  but  it  is  much  less  valuable  than 
Paris  green  on  account  of  the  frequent  occurrence  of  free  arsenic 
which  causes  burning  of  the  foliage. 

White  arsenic  should  not  be  used  on  cotton.  It  will  kill  the  cater- 
pillars, but  will  burn  the  foliage  to  such  an  extent  that  it  does  more 
harm  than  good. 

METHOD    OF   APPLYING   THE   POISON". 

The  method  of  application  by  means  of  sacks  applied  to  a  pole 
carried  on  horseback  through  the  fields,  which  came  into  general  use 
some  years  ago.  will  be  found  to  be  perfectly  satisfactory.  By  this 
means  a  single  farm  hand  can  poison  2  rows  at  a  time  and  cover 
about  20  acres  during  a  day. 

Tli.'  apparatus  for  making  the  application  is  simple.  A  >trip  of 
hardwood  3  inches  in  width.  1  inch  thick,  and  1  font  longer  than  the 
distance  between  the  rows  should  be  selected.  Two  1-inch  holes 
should  be  bored  through  the  >tick  6  inches  from  either  end.  The 
>aeks  to  contain  the  poison  should  made  of  8-ounce  duck  or  similar 
material.  Flour  sacks  will  answer  the  purpose,  but  when  powdered 
arsenate  of  lead  i>  used,  two  thicknesses  will  he  required  on  account" 
of  the  extreme  fineness  of  the  poison.     The  >ack-  should  measure  6 


THE  COTTON  WORM  OB  COTTON  CATERPILLAR.  '.' 

by  20  inches  and  should  be  left  open  on  one  of  the  long  sides.    The 
open  margins  are  then  tacked  on  the  ends  of  the  pole,  forming  a 
which  i-  to  be  filled  with  the  poison  by  mean-  of  a  funnel  inserted  in 
the  auger  hole. 

Care  should  be  taken  to  determine  whether  the  right  amoui.' 
D  is  being  applied.  Tlu-  can  be  easily  don*-  by  weighing  the 
pole  and  sacks  before  and  after  a  known  area  has  been  treated. 
Unless  this  is  done  there  is  likely  to  be  a  waste  resulting  from  the 
application  of  too  much  poison,  or  it  may  be  found  that  the  amount 
that  is  being  applied  is  insufficient  to  cover  the  cotton.  The  operators 
should  be  instructed  to  see  that  the  poison  falls  evenly  upon  the 
plants.  If  too  much  or  too  little  is  being  applied  the  amount  can  be 
easily  regulated  properly  by  varying  the  amount  of  jarring  of  the 
pole.  It  i>  important  that  the  sacks  do  not  come  into  contact  with 
the  cotton  1>  -  If  they  do  the  poison  will  n<>t  pass  th: 
readily  and  it  will  be  found  that  the  amount  applied  is  too  small. 

CAUTION". 

Arsenate  "f  lead  and  the  other  arsenicals  t<>  which  reference  has 
been  made  are  violent  poisons,  but  there  is  no  danger  in  their  us 
cotton  if  a  few  common-sense  precautions  are  taken.  The  only 
of  poisoning  of  dome-tic  animals  known  have  been  where  stock  was 
allowed  to  break  into  the  cotton  fields  soon  after  poisoning  or  where 
some  of  the  poison  was  carelessly  thrown  upon  the  grass.  The  only 
precautions  that  are  necessary  are  to  keep  live  stock  out  of  the 
fields  after  poisoning  and  to  avoid  throwing  any  of  the  poison  on 
tation  that  will  be  devoured  by  live  stock.  It  is  advisable  in 
some  i  ses  to  muzzle  the  mules  upon  which  the  riders  are  mounted 
when  the  application  is  being  made. 

There  is  practically  no  danger  of  poisoning  live  stock  after  one  or 

two  heavy  rains  subsequent  to  the  application  of  the  poison,  or,  in 

'10  rain  fall-,  after  an  interval  of  about  three  week-  has  elapsed. 

The  arsenical  poisons  __  ivatewounds  -  -  >>n  manor  domestic 
animal-.  I  -  quently  all  places  where  the  skin  has  been  broken 
should  be  covered  by  some  mean-,  or  at  any  rate  washed  carefully 
after  the  work  has  been  done.  In  order  to  avoid  the  possibility  of 
injury  to  the  mule-,  it  is  advisable  to  throw  several  buckets  of  water 
over  them  after  the  work  i-  done. 

-      •  I  MARY. 

For  the  control  of  the  cotton  worm  the  use  of  powdered  arsenate 

of  lead  at  the  rate  of  2  pounds  per  acre  is  advised  above  all  other 

mean-.     This  substance  doe-  not  need  to  be  mixed  with  any  other 

material.     Pari-  green,  if  used,  should  be  mixed  with  lime  and  flour 

bed. 


UNIVERSITY  OF  FLORIDA 


10         THE  COTTON  WORM  OK  COTTON 

3  1262  09216  5801 

The  work  of  poisoning  the  insect  should  be  undertaken  as  soon  as 
injury  becomes  apparent  in  any  portions  of  the  fields.  By  this  means 
the  expense  of  control  will  be  greatly  reduced. 

In  regions  where  the  boll  weevil  is  abundant  the  planter  should 
take  care  not  to  poison  the  caterpillar  too  early.  If  he  does  so  the 
production  will  certainly  be  reduced.  Where  the  weevil  occurs  in 
considerable  numbers  no  poisoning  for  the  caterpillar  should  be  done, 
unless  there  is  considerable  ragging  of  the  leaves  before  the  earliest 
bolls  are  three-fourths  grown. 

Approved: 

James  Wilson, 

Secretary  of  Agriculture. 
Washington,  D.  C,  April  12,  1912. 


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